This wasn’t corrected until 1967. Originally from 1959, the map was updated in 1961, and this one in particular, given the cover layout was from 1964-1966, after which the OS adopted picture covers.

Originally from 1959, the map was updated in 1961, and this one in particular, given the cover layout was from 1963. This one printed on cloth, condition can be seen in the high res images. No splits or tears or any obvious pen markinhs.